High Frequency P(VDF-TrFE) Copolymer Broadband Annular Array Ultrasound Transducers using High Density Flexible Circuit Interconnect

摘要

A kerfless eight element high frequency ultrasound annular array transducer using 9 μm P(VDF-TrFE) bonded to a highdensity flexible interconnect was fabricated. The flexible circuit composed of Kapton polyimide film with goldelectrode pattern of equal area annuli apertures on the top side of a 50 μm thick Kapton polyimide film. Each elementhad several 30 μm diameter electroplated vias that connected to electrode traces on the bottom side of the Kaptonpolyimide film. There was a 30 μm spacing between elements. The total aperture of the array was 3.12 mm. Thetransducer’s performance has been modeled by implementing the Redwood version of the Mason model into PSpice andusing the Krimholtz, Leedom and Matthaei (KLM) model utilized in the commercial software PiezoCAD. Thetransducer’s performance was evaluated by measuring the electrical impedance with a HP 4194 impedance analyzer,pulse echo response using a Panametrics 5900 pulser/receiver and crosstalk measurement for each element in the array.The measured electrical impedance for each element was 540 Ω and -84° phase. In order to improve device sensitivityan inductor was attached in series with each element to reduce the insertion loss to 33 dB. The measured average centerfrequency and bandwidth of each element was 55 MHz and 50% respectively. The measured crosstalk at the centerfrequency was -45 dB in water.